1. Technical Field
The present invention generally relates to a printed wiring board or semiconductor device having a thermoset-containing, dielectric material and methods for fabricating the same, and more particularly, to a structure and method for fabricating a dielectric material for use in a high performance semiconductor device.
2. Background Art
In the production of organic laminate chip carriers for packaging, dielectric materials are required between the electrically conductive layers. Optimal characteristics for the dielectric layers include: (1) a low dielectric constant; (2) thin layers; (3) dimensional stability; (4) a low coefficient of thermal expansion (CTE); (5) good adhesion to the surrounding conductive layers; (6) ease of processing; and (7) laser drillability.
Heretofore, many have attempted to develop suitable materials, but have fallen short. One such example of this is shown in U.S. Pat. No. 5,506,049 to Swei et al., hereby incorporated by reference. Swei et al. teaches the use of a silica filled polytetrafluoroethylene (PTFE) matrix as a dielectric. Specifically, Swei et al. casts a silica filled PTFE matrix from a dispersion which results in a non-fibrillated structure. Although this structure exhibits adhesion to the surrounding layers, it has been shown to be both dimensionally unstable (exhibiting as much as 20% reduction in thickness) as well as costly and time consuming to process (due to the high temperatures and pressures required to laminate).
Another example of a related material is taught in U.S. Pat. No. 5,652,055 to King et al., hereby incorporated by reference. King et al. teaches the use of an expanded polytetrafluoroethylene (EPTFE) matrix having ceramic particles and thermosetting resin therein. It is easier to process than the dielectric of Swei et al. because the thermosetting resin can be cured at conventional lamination temperatures. It is also easier to handle than the material of Swei et al. because it has a higher strength. However, the material of King et al. has less ability to re-distribute stresses within the package due to its relatively high elastic modulus.
Therefore, there exists a need for a dielectric material that is: (1) suitable for use in high performance chip carriers; (2) does not require the high temperatures and pressures for lamination of the Swei et al. material; and (3) is cost effective to manufacture. More particularly, there exists the need for a dielectric material that provides optimal characteristics. Such characteristics include: (1) a low dielectric constant; (2) reduced thickness; (3) dimensional stability; (4) a low coefficient of thermal expansion (CTE); (5) good adhesion to the surrounding conductive layers; (6) ease of processing; and (7) laser drillability.